Preparation of tetranitromethane



Patented Oct. 13, 1936 PREPARATION OF TETRANITRODIETHANE Joseph A. Wyler, Allentown, Pa., assignor to Trojan Powder Company, a corporation of New York a w No Drawing. ApplicationiJanuar-y zil,1936,

SerlalNo. 61,315 i ..My invention relates to improvements in the preparation "or manufacture of tetranitromethane, and more particularly relates to an improved processufor the manufacture of tetranitromethf: ane at a low temperature and with relatively high yieldsg One; of the objects of my invention is to increase thesafety of the manufacture of tetranitromethane by performing the reactions leading tog-the formation of this body at a low temperature, and another object of my invention is toincrease the yield of tetranitromethane obtained in the chemical process of; its manufacture-by'reducing those reactions which otherwise lead to the formation of undesirable by-products. ,--I have discovered that through the use of certain'catalytic agents the preparation of tetranitromethane bythe action of nitric acid on acetic anhydridemay be conducted at a lower tempera ture than can be used in the absence of such catalysts,;;and; thatin the presence of such catalysts the action-of nitric acid on acetic anhydride proceeds in a very smooth and regular manner, and with yields up to,80% of theory.

The main reaction which probably occurs when nitric acid acts on acetic acid isrepresented by the following equation:

4(C'H CO)z O-|-4 HNO3'= C(NO2)4+CO2+7CH3COOH It'is recognized that although the above equation probably represents the main reaction there are also anumber of other. reactions which occurat' thesame time that'the main reaction occurs, and which result in the, formation of a 1 number. of, undesirable by-products. Even by the usexof ,my preferred catalysts I am not able to entirely avoid. these undesirable side-reactions that lead to the formation ofuseless by-products and which reduce the yield of tetranitromethane formed;:but by the use of myprocess I am able'to obtain tetranitromethane of a higher purity than is\,possible by the use of other processes now known,,and I am also able to obtain a higher ride, phosphorus pentachloride, sulfuric acid, sulfuryl chloride, boron triacetate, acetyl chloride, hydrochloric acid,,or mixtures .of these, and particularly 'wh'en acetic anhydride and nitric acid react in the presence of any of the above catalysts or of mixtures of any of, the above catalysts in comm. (01. 260-144) the presenceof sharp angular pieces of quartz, glass or like material insoluble in water and in the reacting mixture, the reaction proceeds not only at a lower temperature than in the absence of such assisting materials, but also proceeds much more uniformly: and smoothly, and with the avoidance of the formation of large quantities of by-products, and accordingly with the production of a higher yield of tetranitromethane.

I have further discovered that in the presence of glacial acetic acid, as by diluting the acetic anhydride'or the nitric acid or the mixture of acetic anhydride and nitric acid with glacial acetic acid, in the presence of any of the above catalysts, the operation becomes even more uniform than in the absence of such glacial acetic acid, and the reactlon proceeds at an even lower temperature than in the absence of such glacial acetic acid, although the yield is not quite as good as when the reacting mixture is undiluted by the presence of glacial acetic acid,

process for the manufacture of tetranitromethane may be carried out eithercontinuously or in individual batches. In the continuous process of manufacture I mayladd acetic anhydride and nitric acid simultaneously or intermittently to a mixture of nitric acid, acetic anhydride and catalyst that is already in partial reaction, and in which the reaction has proceeded to the extent of about 20% of theory, for example. I may, for example, continuously feed a reaction mixture of acetic anhydride, nitric acid and catalyst to a tower or a series of towers filledwith quartz, drawing the final product of reaction either continuously or intermittently from a suitable opening at the bottom of the tower.

,In thediscontinuous or vat process I may use any suitable tank, preferably provided with a stirrer, and preferably provided with cooling coils.

I find that cooling to keep the temperature lower than 40? C. during thereaction period is desirable, and I find that the optimum temperature is about 15? C. The temperature can be regulated .by the rate, of addition of the reagents, as well as'by the extent of cooling applied to the reaction vessel, and preferably I employ these two methods in conjunction, the reaction mixture being cooled by the circulation of a cooling fluid through suitable pipes or coils, and the rate of addition of the reagents being so controlled that the temperature will not exceed the desired maximum of 40 C., as any temperature higher than this results in a loss of yield.

The proportions ofnitric acid and acetic anhydride may be varied slightly from the proportio ns'indicated by theory, and I find that'a slight excess of nitric acid over that required by theory is desirable. I prefer to use from 2% to 10% of catalyst, based on the weight of nitric acid used,

'anqrma add the catalyst "at any convenient time and in any convenient manner, provided 1 the catalyst is; present in the;re.action,rnixture,

during the majo r portion' of thereactign betyv the nitric-acid and the acetic anhydride.

r The following specific embodiments will illus trate the methods and proportions which I 'pre fer to use in the'practice of niy inventior'ii Example 1.' 2.7parts of sulfuryl chloride are dissolved in 200 partsjof commercial acetican=' hydride and this mixture "seeded to I36 parts of 99% nitric acid containedi n a tank provided "with a stirrer; a reflux condenser "and ma cooling "Th'e rate :of addition of the mixtu 'sulfuryl chloride f and V acetic "anhydride -rto; the nitric acid should preferablybe slow, so that the temperature i will notl'rise' higher than 20 C. 'a't i f iT ezre ct qni' odu z l' r f n an x b water toprecipitate the tetranitromethane;which;

separates as a lower layer. iThe w'ater'la yeriwillv contain some jtetranitroinethane which will "not go; into' the lower layer containing the 'mainbodyf; of the tetranitromethane'; and 1 this H te tranitro c. methane contained thejwaterfmixture' may be: 5 eco ered y' disti a on; ijt e s ua an any time during the addition; The 'bottomfof thetank may 'be provided with a *layer of sharp pieces of quartz or other angular solid, although ;thisfis not essentialg- 'l'li e re'action m nd-reds: stirred. slowly until-the reaction is complete thisf requiring 7 from #18, 'hours to, -5"- days according} to the rtemperature'at whi" H 1 mai t n d; a d th s tem r s a e e exceed 40 QC. at any 1 time 7 during'gthe' progress ptithereactiOn r with steam.*

flhe tetranitromethane is washed first water,j; thengwithja 72% solution of'sodium biwater. The. tetranitromethane "separates as a l r Colorless l u and ndert en ii o s 1EE' i d nl h g xamp h y lv illc mtf 430% of the theoretical yield f. 1

I Example 2.-'-By using a mix parts o fl99 nitric acid, but otherwiseproceed 7 ingthe sameas in Exampl'e'l, tetranitromethaiie the/theoretical yield. 1

willfbegobtained with'a: yield f about; 70%

Example 3. Using of parts of sulfuric acid in] 148 parts of 99%;cnitficgaoid; and

. utlinedunder Example], fa go od y i'eld of't 'tr 'ji nitrome'thane can be obtained; 7 1

hydride; and maintaining the temperature lower than 20? ,C..'and conductingthe reaction in all other respects in accordance with the procedure Example, j,4.+3 parts of J sulfu V i de n '1 part b facetylg.

' 'z Qqjparts ofcacetic anhydride are admixed' with /4 75 V the temperature" beiow=-20 In" all other. re-- 7 lo l d ss lved inf arts of 99%"nitricgacidwhile In intaining h; the; reacting mass is" i hm v V will beevident that many changes may be made within the scope of the disclosure of my invention herein given, and accordiiigly 'no limi v c a c. bfiZWbai s; off'aceticanhydride and; 5.5 parts? of phosphorus" pentachloride,i and 7 adding jthisf mixture to 148' 7 ril -di i are dissolved'in 2 p'arts' of aceticanhydride and this; mixture is added, to a;imixture offl lfifparts of 99% nitric acid and. 3 parts of g's'ul fu'ric acidl j The temperature is maintainedjbelowfzbf' Cg: during, mejmiszm or the reagentsg'and in all otherreispectsp the reactiongis conducted in accordance w h e r d re out in d i er, Exa e 1- spects the same procedure is followed as given under Example 1.

Many other examples could be given, but it is believed that the above will clearly indicate the characteristic features of my invention. When sulfuric acid is used as the catalyst I may use ,an amount of sulfuric acid equal to,10% of the weight of thenitric acid used, butIdo not find that so high a percentage of catalyst is necesin order to obtain the advantages of my invention, and in general I prefer to use an lan'iount' -ofl catalystto the extent of from 1% to 61% of theweight of nitric acid used. I may vany cat'alystgfrqnrthe list which I have given herein, either alo ejor in admixture with one or In o re pther assisting agents from the list given. may var the order of the addition of the eact'in'g materials, and I may use nitric acid ,;;..of anygayailable strength from a strength of 93% upto chemically pure nitric acid, and I may vary the relative proportions of nitric acid to aceticanhy'dride although I prefer to use substantially the theoretical proportions of'my *reacting "materials',fwith a 'veryslight excess of nitric acid: I .7 v

":It' will of course' b'e levident'that I mayiv'ary the mechanical operations involved in the described reaction as to both thenature of the vessels employed and 'as to the nature of -the V operationsinvolved 'and -my inventiojn is not tb'bejlimite'dtoany of the mechanical'steps that I have'describedjas my invention relates more particularly 'tofthe' chemical reactions which" is onlyincidentally-modified or'controlled by such mechanical steps as stirring, refluxing, cooling,

tations should be placed upon my invention except'as' indicated in thej'appended claims. 'I"claim:"- 1

' 1. In the process of makingtetranitrornethane the {step whichpo'n' prises v reacting facetic' anhy- 7 dride' and nitric acid in'the presence of a member of the group consisting of phosphoricacid, phosphoric pentoxide, phosphorus oxychloride, phosphorus trichloride, -phospho'rus pentachloride, sulfuric acid, 'sufuryl' chloride, boron triac/etate; acetyl chloride and hydrochloricracid.

oxide', phosphorusoxy'chloride, phosphorus tricl'iloride, phosphorus pentachloride, sulfuric acid, sulfuryl chloride, borontriacetatefacetyl chloride andhydrochloric'acid. 7

'4; I11 ,the'proc'ess' of making;tertanitroinethane the "s't'ep W which comprises 7 reacting acetic anhydride and nitric acidjat a temperature lower than 4Q? 'C in the. presence of an assistingagent selected from the'gr oup consisting of phosphoric acid, phosphoric pentoxide, phosphorus 'oxych'loride, phosphorus trichloride, phosphorus pentachloride, sulfuric acid, sulfuryl chloride, boron triacetate, acetyl chloride and hydrochloric acid.

5. In the process of making tetranitromethane the step which comprises reacting acetic anhydride, acetic acid and nitric acid at a temperature lower than 40 C. in the presence of angular particles of a substance insoluble in water and insoluble in the reacting mixture, in the presence of an assisting agent selected from the group consisting of phosphoric acid, phosphoric pentoxide, phosphorus oxychloride, phosphorus trichloride, phosphorus pentachloricle, sulfuric acid, sulfuryl chloride, boron triacetate, acetyl chlo- 15 ride and hydrochloric acid.

6. In the process of making tetranitromethane the step which comprises the reacting of nitric acid and acetic anhydride at a temperature below 40 C. in the presence of additional acetic acid over and above that formed in the reaction itself in the presence of angular particles of a substance insoluble in water and insoluble in the reacting mixture, in the presence of an assisting agent selected from the group consisting of phosphoric acid, phosphoric pentoxide, phosphorus oxychloride, phosphorus trichloride, phosphorus pentachloride, sulfuric acid, sulfuryl chloride, boron triacetate, acetyl chloride and hydrochloric acid.

JOSEPH A. WYLER. I 

